Discussion :

[Tenebrous]

Bonjour,

Dans le cadre d'un projet, je dois réécrire 3 fonctions assez techniques (en rapport avec des CRC). Lorsque je fais tourner le programme, j'ai justement une erreur dans les CRC (les valeurs ne sont pas correctes).
Je n'ai pas réussi à trouver l'erreur mais je suis certain qu'elle se trouve dans une des 3 fonctions suivantes. Si certains d'entre vous s'y connaissent suffisamment en VB et C++ pour me dire si j'ai bien traduit les fonctions, ce serait sympa

Première fonction
Version VB :

Code :

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Public Function OutFile_CRC16ComputeOnPartOfFile(lOStart As Long, lOEnd As Long) As Long
  Dim lIx As Long, b As Byte, Ix As Integer
  Dim lmodE As Integer, ldivE As Long, lmodS As Integer, ldivS As Long
  Dim mskE As Byte, mskS As Byte
 
  ldivS = 1 + (lOStart \ 8) 
  lmodS = lOStart Mod 8
  mskS = &HFF
  For Ix = 1 To lmodS: mskS = mskS \ 2: Next Ix
 
  ldivE = 1 + (lOEnd \ 8) 
  lmodE = lOEnd Mod 8
  mskE = &H7F
  For Ix = 1 To lmodE: mskE = mskE \ 2: Next Ix
  mskE = Not mskE
 
  Call OutFile_CRC16Init
  If ldivS = ldivE Then
    Call OutFile_CRC16Init
    Get #fOut, ldivS, b
    b = (b And mskS) And mskE
    Call OutFile_CRC16UpdCRC(b)
  Else
    lIx = ldivS
    Get #fOut, lIx, b
    Call OutFile_CRC16UpdCRC(b And mskS)
    lIx = lIx + 1
    While (lIx < ldivE)
      Get #fOut, lIx, b
      Call OutFile_CRC16UpdCRC(b)
      lIx = lIx + 1
    Wend
    Get #fOut, lIx, b
    Call OutFile_CRC16UpdCRC(b And mskE)
  End If
 
  OutFile_CRC16ComputeOnPartOfFile = OutFile_CRC16GetCRC
End Function

Version C++ :

Code :

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long __fastcall ModOutFile::outFileCRC16ComputeOnPartOfFile(long lOStart, long lOEnd)
{
   long lIx, ldivE, ldivS;
   unsigned char b, mskE, mskS;
   int lmodE, lmodS;
 
   ldivS = 1 + (lOStart / 8); 
   lmodS = lOStart % 8;
   mskS = 0xFF;
   for(int ix = 1; ix <= lmodS; ++ix)
        mskS /= 2;
 
   ldivE = 1 + (lOEnd / 8);  
   lmodE = lOEnd % 8;
   mskE = 0x7F;
   for(int ix = 1; ix <= lmodE; ++ix)
        mskE /= 2;
   mskE = ~mskE;
   outFileCRC16Init();
   if(ldivS == ldivE)
   {
        outFileCRC16Init();
        fseek(fOut, ldivS * sizeof(char), SEEK_SET);
        fread(&b, sizeof(char), 1, fOut);
        b = (b & mskS) & mskE;
        outFileCRC16UpdCRC(b);
   }
   else
   {
        lIx = ldivS;
        fseek(fOut, lIx * sizeof(char), SEEK_SET);
        fread(&b, sizeof(char), 1, fOut);
        outFileCRC16UpdCRC(b & mskS);
        ++lIx;
        while(lIx < ldivE)
        {
                fseek(fOut, lIx * sizeof(char), SEEK_SET);
                fread(&b, sizeof(char), 1, fOut);
                outFileCRC16UpdCRC(b);
                ++lIx;
        }
        fseek(fOut, lIx * sizeof(char), SEEK_SET);
        fread(&b, sizeof(char), 1, fOut);
        outFileCRC16UpdCRC(b & mskE);
   }
   return outFileCRC16GetCRC();
}

Deuxième fonction
Version VB :

Code :

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Public Sub OutFile_Rewrite32bits(lOffset As Long, lValue As Long)
  Dim ldiv As Long, lmod As Integer, bOldMode As Boolean, Ix As Integer
 
  bOldMode = bPutBitFixupMode
  Call OutFile_Purge
  bPutBitFixupMode = True
  ldiv = 1 + (lOffset \ 8) 
  lmod = lOffset Mod 8
  Get #fOut, ldiv, PutBitByte
  PutBitMask = &H80
  For Ix = 1 To lmod: PutBitMask = PutBitMask \ 2: Next Ix
  PutBitOffset = lOffset
  PutBitRecNum = ldiv
 
  Call OutFile_PutValue(lValue, 1, 32)
  Call OutFile_Purge
  bPutBitFixupMode = bOldMode
End Sub

Version C++ :

Code :

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void __fastcall ModOutFile::outFileRewrite32bits(long lOffset, long lValue)
{
   bool bOldMode;
   long ldiv;
   int lmod;
 
   bOldMode = bPutBitFixupMode;
   outFilePurge();
   bPutBitFixupMode = true;
   ldiv = 1 + (lOffset / 8);
   lmod = lOffset % 8;
   fseek(fOut, ldiv * sizeof(char), SEEK_SET);
   fread(&putBitByte, sizeof(char), 1, fOut);
   putBitMask = 0x80;
   for(int ix = 1; ix <= lmod; ++ix)
        putBitMask /= 2;
   putBitOffset = lOffset;
   putBitRecNum = ldiv;
   outFilePutValue(lValue, 1, 32);
   outFilePurge();
   bPutBitFixupMode = bOldMode;
}

Troisième fonction
Version VB :

Code :

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Public Function OutFile_PutValue(ByVal sv As String, ByVal cResol As Double, ByVal NumberOfBits As Integer, Optional StringSize As Integer) As String
 
Dim Final As String, Ix As Integer, re As Byte, v As Double
  Dim ForLog As String
  Dim iSS As Integer
  Dim aze As Double
 
  OutFile_PutValue = "?"
  If NumberOfBits <> NUMBITSSTRING Then
     If NumberOfBits < 1 Then
        Exit Function
     End If
  End If
 
  ForLog = OutFile_GetPutBitOffset
  If NumberOfBits = NUMBITSSTRING Then
    iSS = Abs(StringSize)
    If Len(sv) > iSS Then
       If bLogging Then Call AppendLog(LOGERROR, "Length of '" & sv & "' exceeds asked for length (" & iSS & ")")
       nErrors = nErrors + 1
    End If
    sv = Left(sv & Space(iSS), iSS)
    OutFile_PutValue = sv
    For Ix = 1 To iSS
      If StringSize < 0 Then
        Call OutFile_PutValue("0", 1, 8)
        Call OutFile_PutValue("0", 1, 8)
        Call OutFile_PutValue("0", 1, 8)
      End If
      Call OutFile_PutValue(CStr(Asc(Mid(sv, Ix, 1))), 1, 8)
    Next Ix
    Exit Function
  End If
 
  On Error Resume Next
  v = CDbl(sv)
  If Err.Number <> 0 Then
    v = 0: Err.Clear
  End If
  If cResol <> 1 Then
     If cResol <> 0 Then
        v = CDec(v) / CDec(cResol) 
     End If
  End If
  Final = String(NumberOfBits, "0")
  For Ix = 1 To NumberOfBits
    re = CMod(v, 2)
    v = Int(CDec(v) / 2) 
    If re <> 0 Then Mid(Final, NumberOfBits - Ix + 1, 1) = "1" 
  Next Ix
  For Ix = 1 To NumberOfBits
    If Mid(Final, Ix, 1) = "1" Then Call OutFile_PutBit(1) Else Call OutFile_PutBit(0)
  Next Ix
  OutFile_PutValue = Final
  If bLogging Then
	If OutFile_bHidden Then
		If bLogging Then Call AppendLog(LOGINFO, ForLog & " > " & NOTVISIBLESTRING)
	Else
		If bLogging Then Call AppendLog(LOGINFO, ForLog & " > " & Final)
	End If
  End If
End Function

Version C++ :

Code :

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String __fastcall ModOutFile::outFilePutValue(String sv, double cResol, int numberOfBits, int stringSize)
{
   String ret, forLog, final;
   int iSS;
   double v;
   unsigned char re;
 
   ret = "?";
   if(numberOfBits != NUMBITSSTRING)
   {
        if(numberOfBits < 1)
                return ret;
   }
   forLog = outFileGetPutBitOffset();
   if(numberOfBits == NUMBITSSTRING)
   {
        iSS = abs(stringSize);
        if(sv.Length() > iSS)
        {
                if(bLogging)
                        appendLog(LOGERROR, "Length of '" + sv + "' exceeds asked for length (" + iSS + ")");
        }
        //construct spaces string
        String iSSSpaces = "";
        for(int i = 0; i < iSS; ++i)
                iSSSpaces += " ";
        String svWithSpaces = sv + iSSSpaces;
        sv = svWithSpaces.SubString(1, iSS);
        ret = sv;
        for(int ix = 1; ix <= iSS; ++ix)
        {
                if(stringSize < 0)
                {
                        outFilePutValue("0", 1, 8);
                        outFilePutValue("0", 1, 8);
                        outFilePutValue("0", 1, 8);
                }
                //get ASCII value here because no Asc() function in C/C++
                String car = sv.SubString(ix, 1);
                int val = *(car.c_str());
                outFilePutValue(IntToStr(val), 1, 8);
        }
        return ret;
   }
 
   try { v = StrToFloat(sv); } // careful if , or .
   catch(EConvertError &e) { v = 0; }
   if(cResol != 1)
   {
        if(cResol != 0)
                v /= cResol;
   }
   //best way i found to init string with a certain number of characters
   std::string finalC = std::string(numberOfBits, '0');
   final = finalC.c_str();
   for(int ix = 1; ix <= numberOfBits; ++ix)
   {
        re = cMod(v);
        v = (int) (v/2);
        if(re != 0)
                final[numberOfBits - ix + 1] = '1';
   }
   for(int ix = 1; ix <= numberOfBits; ++ix)
   {
        if(final.SubString(ix, 1) == "1")
                outFilePutBit(1);
        else
                outFilePutBit(0);
   }
   ret = final;
   if(bLogging)
   {
        if(outFilebHidden)
                appendLog(LOGINFO, forLog + " > " + NOTVISIBLESTRING);
        else
                appendLog(LOGINFO, forLog + " > " + final);
   }
   return ret;
}

Je sais qu'il y a des appels à d'autres fonctions mais ces dernières sont correctes.
Merci d'avance.